WO2014198267A1

WO2014198267A1 - Piston/cylinder arrangement for a hydraulic disengagement device, in particular a master cylinder for a hydraulic shift actuating device

Info

Publication number: WO2014198267A1
Application number: PCT/DE2014/200209
Authority: WO
Inventors: Jan Grabenstätter; Julien Oster
Original assignee: Schaeffler Technologies Gmbh & Co. Kg
Priority date: 2013-06-10
Filing date: 2014-05-13
Publication date: 2014-12-18
Also published as: CN105283686A; CN105283686B; EP3008357B1; EP3008357A1; DE102014209026A1; DE112014002766A5

Abstract

The invention relates to a piston/cylinder arrangement, in particular a master cylinder for a hydraulic shift actuating device, comprising a housing in which a piston is mounted in an axially movable manner. A primary chamber is defined upstream of the piston in the piston actuation direction, said primary chamber being sealed from a secondary chamber between the housing and the piston by means of a primary seal which radially encircles the piston. The aim of the invention is to provide a piston/cylinder arrangement which allows a replenishing function within the piston/cylinder arrangement in a structurally simple manner. This is achieved in that the primary seal is arranged on a slide which radially covers the piston in an axially movable manner, wherein a radial overrun gap between the primary chamber and the secondary chamber is opened or closed dependent on the position of the slide.

Description

Piston-cylinder arrangement for a hydraulic release device, in particular a master cylinder for a hydraulic clutch actuator.

The invention relates to a piston-cylinder arrangement for a hydraulic clutch release device, in particular a master cylinder for a hydraulic clutch actuator, comprising a housing in which a piston is mounted axially movable, wherein in front of the piston in the actuation direction, a primary space is clamped, which by means of a , the piston radially spanning primary seal is sealed against a secondary space between the housing and the piston.

Hydraulic master cylinder, as found in Kupplungsbetätigungssystemen application, consist of a housing in which a piston is mounted axially movable. In front of the piston, a primary space is clamped, in which a hydraulic fluid is shifted towards the slave cylinder. A secondary space, which is connected to a reservoir, is located between the piston and the housing. The housing comprises a groove, via which the primary chamber is connected to the secondary chamber with a corresponding position of a primary seal arranged on the piston, in order thereby to be able to exchange hydraulic fluid. In order to avoid excessive negative pressures in the primary space, master cylinder are known in which the negative pressure in the primary chamber sucks hydraulic fluid from the secondary chamber into the primary chamber via a check valve. The check valve is designed, for example, as a plate valve or a spring check valve. Valves are also known in which a liquid passage is realized by folding over the sealing lip on the primary seal. The use of plate valves or spring check valves represents the use of additional components that require an increased space requirement of the release device. Such valves are sensitive to contamination and fulfill the Nachsaugfunktion only when negative pressures in the primary space already occur. Even with a folding sealing lip on the primary seal there is an increased risk of contamination, with the Nachsaugfunktion is executed only when greater negative pressures occur.

The invention is thus based on the object to provide a piston-cylinder arrangement for a disengaging device, in particular a master cylinder for a hydraulic Kupplungsbetä- tigungseinrichtung, in which a Nachsaugfunktion is reliably implemented despite reduced space. According to the invention the object is achieved in that the primary seal is arranged on a carriage which axially movable piston comprises radially, wherein depending on the position of the carriage, a radial caster gap between the primary space and the secondary space is opened or closed. The carriage as a carrier of the primary seal allows easy movement of the primary seal. Depending on the position of the carriage, which performs a relative movement to the piston, a connection between the primary space and the secondary space of the piston-cylinder arrangement is released, whereby the suction of the hydraulic fluid to prevent a strong negative pressure in the primary space. Due to the relative movement of the carriage to the piston, an extremely sensitive suction of the hydraulic fluid from the secondary space into the primary space is made possible. On additional components is omitted, which leads to the reduction of the installation space of the piston-cylinder arrangement. Dirt on the interior of the case are prevented.

Advantageously, the carriage carrying the primary seal has an axial clearance to the piston for the axial movement of the primary seal, in which the primary seal is guided in a sliding manner on the housing. By means of this game, the carriage and thus the primary seal in response to a pressure in the primary space and the friction between the primary seal and the housing is brought into a position in which the Nachsaugspalt between the secondary space and primary space is automatically opened or closed.

In one embodiment, a seal backing extends beyond the carriage in the axial direction of the piston, wherein the axial extent of the seal including the seal back is smaller than the play of the carriage. The position of the seal back determines whether the trailing gap between the secondary space and the primary space is present and thus whether a Nachsaugvorgang can take place.

In a variant of the sealing back is at a forward stroke of the piston to this, while in a return stroke of the piston, the trailing gap between the seal back and the piston is open, which forms a connection between the primary space and the secondary space. Only the movement of the carriage realizes a reliable connection between the secondary and the primary space without the need for additional components. In a further development, the primary seal is made of a material with high frictional properties with respect to the material of the housing, the carriage and / or the piston, while the housing, the carriage and the piston consist of materials which have approximately the same friction properties. Due to these properties, the Nachsaugen pressure and friction controlled. Since the primary seal is mounted on a, to a certain extent on the piston axially displaceable carriage, the friction between the housing and the primary seal is greater than between the piston and the primary seal. As the piston advances, the friction helps to push the seal back against the piston, sealing the overrun gap between the primary and secondary seals. Due to the pressure that builds up during the Vorhubbewegung in the primary space and thereby acting on the primary seal axial force is the seal self-reinforcing. Since the friction force of the primary seal on the housing is greater than the compressive force acting on the primary seal during the return stroke, the frictional force pulls the primary seal away from the piston and the trailing gap is opened. Now the hydraulic fluid can flow from the secondary to the primary chamber along the seal back.

Advantageously, the primary seal consists of an elastomer, wherein the piston and / or the housing are made of a plastic. By this configuration, the Nachsaugvorgang is already activated when there is still a slight overpressure in the primary space. The Nachsaugvorgang thus responds to a return stroke very quickly.

In one embodiment, a sliding seal and the sealing back of the primary seal are injection-molded radially opposite to the carriage, wherein the sliding seal and the sealing back are preferably axially offset from each other. By injecting the sliding seal and the seal back to the carriage creates a complex two-component component, which is easy to handle during assembly of the piston-cylinder assembly.

In one variant, the sliding seal has a main sealing lip and subsequently a "sensitive" sealing lip, which extend radially in the direction of the piston, the "sensitive" sealing lip surmounting the main sealing lip. This not only ensures high sensitivity of the sliding seal against pressure differences, but also allows a seal against contamination at the same time. Alternatively, the sliding seal, the sealing back and arranged between the sliding seal and sealing back, extending parallel to the direction of movement of the piston base are integrally formed and approximately enclose the carriage. The use of two separate components such as the one-piece primary seal, which is composed of sliding seal, sealing back and base, and the slide allows the setting of a good preload of the primary seal when mounted on the carriage, which increases the sealing properties of the primary seal.

In a variant, the carriage has an annular, spaced from the piston on this protruding extension. With the help of this extension, a filter is created because larger contaminants, which do not fit between an axially circumferential gap between the piston and extension of the sealing back and thus of the trailing gap, through which the hydraulic fluid is passed from the secondary chamber into the primary space, kept away.

In a further development, an end face of the piston pointing in the direction of the primary space is closed by a plug-like element which has a radial projection for limiting the maximum relative movement of the carriage relative to the piston.

Advantageously, the carriage is designed as a sliding ring. Such a sliding ring is a cost-effective component, which can be mass-produced and thus further reduces the cost of producing the piston-cylinder assembly.

The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures shown in the drawing.

It shows

FIG. 1 shows a schematic representation of a hydraulic coupling system,

2 shows a first embodiment of the piston-cylinder arrangement according to the invention,

3 shows a second embodiment of the piston-cylinder arrangement according to the invention, 4 shows a third embodiment of the piston-cylinder arrangement according to the invention,

5 shows a fourth embodiment of the piston-cylinder arrangement according to the invention,

Figure 6: a fifth embodiment of the piston-cylinder arrangement according to the invention.

Identical features are identified by the same reference numerals.

1 shows a schematic diagram of a hydraulic clutch actuation system 1 is shown. In this case, a donor side 2 is connected via a pressure line 3 to a slave side 4. The encoder side 2 in this case comprises a master cylinder 5, which has a cylindrical housing 6, in which an axially mounted piston 7 is movable. The piston 7 is driven by an actuator, not shown, which is realized by a control device or an accelerator pedal. The master cylinder 5 comprises a primary chamber 8, in which a hydraulic fluid 9 is arranged, which is transported by the pressure line 3 to a slave cylinder 10 on the slave side 4 by a movement of the piston 7 of the master cylinder 5. By moving over the master cylinder 5 hydraulic fluid 9, a piston 1 1 of the slave cylinder 10 is moved, which actuates a coupling 13 via a release bearing 12.

A first embodiment of a piston-cylinder arrangement according to the invention will be explained with reference to the master cylinder 5, which is shown in Figure 2. On the side facing the primary chamber 8 side of the piston 7, a radial primary seal 14 is circumferentially arranged. This primary seal 14 is positioned on a slide ring 15, which rests directly on the piston 7. The primary seal 14 contacts the inside of the housing 6 with its radial edge. In addition, the primary seal 14 has a sealing back 16, which in the axial direction projects beyond the sliding ring 15 made of a plastic in the direction of the piston 7.

Between the made of a plastic piston 7 and the likewise made of a plastic housing 6, the primary seal 14 is remote, a secondary space 17 is formed, which via a bore 18 with a reservoir 19 (Figure 1) in conjunction stands. Such a connection is necessary to allow a volume compensation of the hydraulic fluid of the hydraulic system with temperature fluctuations. In FIG. 2, the lower half of the illustration shows the piston 7 in a preliminary stroke V, while the upper half of the illustration shows the piston 7 in the return stroke R. The existing of an elastomer primary seal 14 is pulled in a so-called sniffing, the suction of the hydraulic fluid from the reservoir 19, behind a Schnüffelnut 20, which is formed on the inside of the housing 6 near the bore 18. Through this Schnüffelnut 20 a connection between the primary space 8 and the reservoir 19 is created.

Since the primary seal 14 is made of a material with higher friction than the housing 6 or the sliding ring 15, the friction occurring between the housing 6 and the primary seal 14 is friction larger than that between the piston 7 and the slide ring 15. In the preliminary stroke V, the friction helps the seal back 16, which projects beyond the slide ring 15 in the axial direction in the direction of the piston 7, against the end face of the piston 7. As a result, there is no connection between primary and secondary chamber 8, 17. The piston 7 is completely sealed by the seal back 16. Due to the pressure that builds up during the Vorhubbewegung in the primary chamber 8 and thereby acting on the primary seal 14 axial force sealing is self-reinforcing. When the return stroke R, the friction force of the primary seal 14 on the housing 6 is greater than acting on the primary seal 14 pressing force of the hydraulic fluid 9 in the primary chamber 8, the primary seal 14 is pulled away from the piston 7. A caster gap 21 is formed in the radial direction between the seal back 16 and the piston 7. Hydraulic fluid can now flow from the secondary chamber 17 into the primary chamber 8 along the seal back 16 in order to prevent an excessively high underpressure in the primary chamber 8. Thus, the Nachsaugmechanismus is always activated when there is still a slight overpressure in the primary chamber 8. The Nachsaugmechanismus therefore responds very quickly during the return stroke.

A second embodiment of the master cylinder 5 is shown in Figure 3, in which Figure 3a shows the master cylinder 5 in a Vorhubbewegung, while Figure 3b indicates a return stroke of the master cylinder 5. In both cases, the primary seal 14 comprises two parts, the lip-shaped sliding seal 14a and the seal back 14b. The sliding seal 14a and the seal back 14b are molded onto the sides of the slide ring 15 extending approximately perpendicular to the wall of the housing 6. The seal back 14b presses against the end wall of the piston 7, while the sliding seal 14a is slidably guided relative to the housing 6. As already described, the seal seals Press back 14b the piston 7 during the forward stroke of the master cylinder 5 completely, so that no connection between the primary chamber 8 and the secondary chamber 17 is present. This is in contrast to Figure 3b, where a return stroke of the piston 7 is illustrated. In this case, between the end wall of the piston 7 and the seal back 14b, the radial tracking gap 21 is released, through which a sensitive subsequent sucking of the hydraulic fluid 9 from the secondary chamber 17 into the primary chamber 8 takes place. Such vacuuming is thus triggered depending on the pressure and friction conditions present in the master cylinder 2.

FIG. 4 shows a preferred embodiment of the lip-shaped sliding seal 14a. The sliding seal 14a comprises a main sealing lip 25 and a "sensitive" sealing lip 26, both of which point radially in the direction of the piston 7 and project beyond the sliding ring 15. In order to realize the function of the main sealing lip 25 and the "sensitive" lip 26, FIG Piston 7 in the area where the sealing lips 25, 26 abut a trained as grading Schnüffelnut 27. The "sensitive" sealing lip 26, which lies directly opposite the primary space 8 and has a longer design than the main sealing lip 25, contacts the piston 7 and seals the master cylinder 5 even at low pressures, since this deforms rapidly the sliding ring 15 and the "sensitive" sealing lip 26 is formed, seals at high pressures. Thus, by these two sealing lips 25. 26 of the sliding seal 14 a reaches a good sensitivity to contamination. In vacuum, the slide ring 15 and the primary seal 14 connected to the slide ring 15 is sucked in, with the main seal lip 25 and also the "sensitive" sealing lip 26 losing contact with the piston 7, wherein hydraulic fluid 9 can flow from the reservoir 19 into the primary chamber 8 ,

Figure 5 shows a fourth embodiment of the master cylinder 5 according to the invention, in which in particular the primary seal 14 is integrally formed. While in Figure 3 and 4 slide ring 15 and primary seal 14 form a two-component component, it is assumed in Figure 4 that the primary seal 14 and the slide ring 15 represent two separate components. In this case, designed as an elastomer primary seal 14, which also has the sliding seal 14a and the seal back 14b, stretched around the slide ring 15. The sliding seal 14 a and the seal back 14 b are connected in the direction of movement of the piston 7 by a base 14 c, which rests on the slide ring 15. Also in this case, the slide ring 15 is pressed by the pressure and friction conditions occurring in the forward stroke against the end face of the piston 7 (Figure 4a), while in the return stroke of the piston 7 shown in Figure 4b of the slide ring 15 with the primary seal 14 against a projection 22 of the piston 7 can be moved maximally to release the radial caster 21 between the seal back 14 b and the end face of the piston 7.

Both in Figure 3 and in Figure 5, the slide ring 15 has an annular extension 23 which projects beyond the piston 7 spaced therefrom. By means of this annular extension 23, an annular gap 24 is formed with the piston 7, which serves as a filter and keeps coarser dirt away from the sealing back 14b.

6 shows a further embodiment of the master cylinder 5 is shown, in particular, a limitation for the maximum relative mobility of the seal ring 15 relative to the piston 7 is illustrated. Thus, an end face of the piston 7, which faces the primary space 8, is closed by means of a plug-like element 28. The plug-like element 28 in this case has a radial projection 29 in the direction of the housing 6, which thus constitutes a stop for the sliding ring 15. Alternatively, the limitation of the slide ring 15 can also be realized via a snap ring or a snap hook.

The described piston-cylinder arrangement with Nachsaugfunktion is used in hydraulic release systems. Due to the mobility of the primary seal 14-bearing seal ring 15, which is used as a carriage, the primary seal 14 receives an axial play, which allows extremely sensitive afterglow.

Reference number list Hydraulic clutch actuation system Encoder side

pressure line

recipient side

Master cylinder

casing

piston

primary space

hydraulic fluid

0 slave cylinder

1 piston

2 release bearing

3 clutch

4 primary seal

4a sliding seal

4b sealing back

14c base

15 sliding ring

16 sealing back

17 secondary room

18 hole

19 reservoir

0 snooping

21 caster gap

22 lead

23 extension

24 annular gap

25 main sealing lip

26 "sensitive" sealing lip

27 sniffing groove

28 plug-like element

29 advantage

V forward stroke

R return stroke

Claims

claims

1 . Piston-cylinder arrangement for a hydraulic disengagement device, in particular a master cylinder of a clutch actuator, comprising a housing (6) in which a piston (7) is mounted axially movable, wherein in front of the piston (7) in the actuation direction of a primary space (8) is clamped, which by means of a piston (7) radially surrounded primary seal (14) against a secondary space (17) between the housing (6) and the piston (7) is sealed characterized in that the primary seal (14) on a carriage ( 15) is arranged, which axially movable piston (7) comprises radially, wherein depending on the position of the carriage (15), a radial trailing gap (21) between the primary chamber (8) and the secondary chamber (17) is opened or closed.

2. Piston-cylinder assembly according to claim 1, characterized in that the primary seal (14) carrying slide (15) for axial movement of the primary seal (14), wherein the primary seal (14) is guided in a sliding manner on the housing (6) , an axial clearance to the piston (7).

3. piston-cylinder arrangement according to claim 2, characterized in that a sealing back (14 b, 16) projects beyond the carriage (15) in the axial direction to the piston (7), wherein the axial extent of the primary seal (14) including the sealing back ( 14b, 16) is smaller than the play of the carriage (15).

4. piston-cylinder assembly according to claim 1, 2 or 3, characterized in that the sealing back (14 b, 16) at a forward stroke (V) of the piston (7) abuts against this, while at a return stroke (R) of the piston (7) the after-run gap (21) between the seal back (14b, 16) and the piston (7) is opened, which forms a connection between the secondary space (17) and the primary space (8).

5. Piston-cylinder arrangement according to one of the preceding claims, characterized in that the primary seal (14) made of a material with high frictional properties against the material of the housing (6), the carriage (15) and / or Piston (7), while the housing (6), the carriage (15) and the piston (7) consist of materials which have approximately the same friction properties.

6. piston-cylinder assembly according to claim 5, characterized in that the primary seal (14) consists of an elastomer and / or the piston (7), the carriage (15) and the housing (6) are made of a plastic.

7. piston-cylinder assembly according to at least one of the preceding claims, characterized in that a sliding seal (14 a) and the sealing back (14 b) of the primary seal (14) are radially opposite to the slide (15) molded, wherein the sliding seal (14 a ) and the sealing back (14b) are preferably axially offset from each other.

8. piston-cylinder assembly according to claim 7, characterized in that the

Sliding seal (14a) has a Hauptdichtlippe (25) and then axially thereafter a "sensitive" sealing lip (26) which extend radially in the direction of the piston (7), wherein the "sensitive" sealing lip (26) surmounting the main sealing lip (25).

9. piston-cylinder assembly according to at least one of the preceding claims 1 to 6, characterized in that the sliding seal (14 a), the sealing back (14 b) and a between sliding seal (14 a) and sealing back (14 b) arranged, parallel to the direction of movement the piston (7) extending base (14c) are integrally formed and approximately enclose the carriage (15).

10. piston-cylinder arrangement according to at least one of the preceding claims, characterized in that the carriage (15) has an annular, spaced from the piston (7) via this projecting extension (23).

1 1. Piston-cylinder arrangement according to at least one of the preceding claims, characterized in that in the direction of the primary space (8) facing end side of the piston (7) with a plug-like element (28) is closed, which has a radial projection (29) for limiting the maximum relative movement of the carriage (15) relative to the piston (7).

12. piston-cylinder assembly according to one of the preceding claims, characterized indicates that the carriage (15) is designed as a sliding ring.